In an absolute positioning system in which pulses of a quantity corresponding to a command displacement, which is obtained by subtracting the present absolute position from a command absolute position, are delivered to effect positioning control, if the present position upon application of power supply is unknown, a reference point return operation must be performed, since the command displacement cannot be precisely calculated on the basis of the command absolute position only. In order to obviate such an awkward situation, as is conventionally known, an absolute position detector, e.g., an absolute pulse encoder, may be subjected to battery-backup so that a detected absolute position upon termination of power supply is retentively stored even after the power is turned off, and the reference point return operation when the power is turned on again can be omitted. As is also conventionally known, feedback pulses, which are generated from a pulse encoder as an object of position detection moves, may be divided by means of interpolation pulses, thereby improving the detection resolution.
However, if an absolute counter and an interpolation counter for counting the feedback pulses and the interpolation pulses, respectively, are both subjected to battery-backup, in order to obtain the advantages of both these prior art arrangements, substantial electric power consumption is required, that is, the system is uneconomical.